1. Field of the Invention
The invention concerns a new arrangement for the reaping platform of harvesting machines with a feed drum supported behind the cutter bar in the direction of motion.
2. Discussion of the Background
The feed drum itself can be designed as a worm or else it can be provided with conveyor prongs or strips which transport the crop. It is immaterial whether the drum and reel are used on the reaping platform of a harvesting machine, i.e. on a machine which cuts and processes the crop, or whether they are used in an acceptance unit which accepts and further processes the cut crop or feeds it to units which undertake the further processing.
The invention can also be employed in machines which only cut the crop and deposit it on a windrow for further handling or processing. In order to simplify the presentation, the invention is described within the operational technology of the reaping platform of a combine harvester, as representative of the various harvesting and reaping machines.
Particularly in the case of combine harvesters, the most widely varied crops have, in recent times, been cut by the reaping platform and supplied to the threshing units via the feed drum and the conveyor elements.
The differences between the field crops to be threshed impose very widely varying requirements on the acceptance function of the reaping platform. The feed drum and the reel play a particularly important role in this respect, both in terms of their adjustment relative to one another and in terms of their adjustment relative to the cutter bar of the reaping platform.
Whereas the ability to adjust the reel, both vertically and horizontally, has now become part of the state of the art, ability to adjust the feed drum has been neglected up to now. The known art only provides the drum with a fixed vertical adjustment and for this purpose, the reaping has to be stopped and the work interrupted. In a further embodiment, the drum is rotatably supported by means of a lever in such a way that it can escape upwards against its weight by a small amount if the quantity of straw arriving is large.
In practical operation, however, it often happens that moist straw, in particular, winds around the feed drum and jams the latter so that it can no longer rotate. The newer combine harvesters have a reversing device specially for this case and this permits the drum to be rotated back against the working direction so that the straw which has wound up can be unwound again. In order to rotate against the working direction, however, a jammed drum requires the said torque as that which occurred when it jammed. The overload safety device must therefore be able to transmit a higher torque for rotation against the working direction in order to ensure that the drum can release itself again. This requires complicated overload safety arrangements.
If the drum could be adjusted vertically and horizontally from the driver's seat, it would be substantially easier to turn the drum back because, of course, the jamming takes place because the straw is squeezed between the reaping platform trough and the drum.
The ability to adjust the drum in the horizontal and vertical directions, however, is even more important from a functional point of view. As an example, rape is usually harvested at the same time of the year as other types of grain. Rape, however, is a type of crop particularly subject to ejection. In order to keep this ejection loss as small as possible during combine harvesting, it is necessary to select a distance between the reaping platform cutting bar and the feed drum which is as large as possible so that the rape grains ejected by the rapidly rotating drum are not thrown in front of the reaping platform and thus lost. In addition, rape straw is much bulkier than, for example, grain straw and has to be pushed under the drum by intensive reel work. Particularly in the case of rape, this causes the reel to break open the husks and the grains are lost if they fall in front of the cutter bar.
With other types of crop, the feed operates better if the feed drum is working closer to the cutter bar.
In addition, it frequently happens that the crop is layered in one direction and it is then necessary to operate with a different distance between the cutter bar and the feed drum for the different reaping directions.
The same applies to operations on hilly or sloping terrain.
In order to make the reaping platforms of such harvesting machines universal, various reaping platform extensions are on offer and most of them are fitted for the rape harvest. The cutter bars are then moved approximately 30-40 cm forward relative to the feed drum and the intermediate space is covered by appropriate metal sheets. The fitting of such a reaping platform extension is very expensive in time and labour.
Various other designs include a reaping platform trough which can be extended by lengthening in the forward direction telescopically, either by means of elongated hole slots, hydraulic cylinders or spindles. Since all these designs require the whole of the cutter bar and the cutter drive to be displaced, they are again very expensive, faults and repair work being frequent because of the lack of stability.